Lean Six Sigma, again a Best Practice, is identified as Scientific Management. It started at the turn of the 20th century where Frederick Winslow Taylor drafted his book The Principles of Scientific Management. He is the Father of Modern Scientific Management.
Supporting him were his contemporaries which included Frank and Lillian and Galbreath, who developed time in motion, and takt time studies; Peter F. Drucker who developed the Management by Objectives, and Ed Deming ,with his 14 Points contributed to the Total Quality Management movement. Bill Smith with his engineers at Motorola, developed the Six Sigma plan using Walter Shewart and his Statistical Process Controls and Druker's MBO theory. Eli Goldratt, after writing his novel The Goal, introduced the Theory of Constraints. Taiichi Ohno developed the Toyota Production Systems, aka TPS that saved the auto manufacture from bankruptcy to be one of the top three companies in the world, and James Womac who translated the Japanese TPS concepts to American engineering and made it “Lean”.
As years passed, concepts and processes were practiced, modified and improved, so were the companies that experienced them.
There are other names and their esteemed backgrounds and contributions, but from a white and yellow belt level, this will give you a start to learning more.
You can easily learn more about them through the Internet. And if you are inclined, feel free to purchase books and abstracts they authored. But for now, try to remember their names and how they fit into the initial learning curve.
Summarizing.

Fredrick Winslow Tayler – Father of Scientific Management

Frank and Lillian Galbreath – Time and Motion Studies

Peter F. Drucker – Management by Objectives

Edward W. Deming – 14 Points and considered father of Total Quality Management

Walter Shewhart - Statistical Process Control

Bill Smith (Motorola) - Six Sigma

Eli Goldratt – Theory of Constraints

Taiichi Ohono – Toyota Production Systems aka TPS

James Womack – Lean Manufacturing